There was speculation that the Republican man of the hour would make an unannounced visit to the convention hall Tuesday night when his wife, Ann, was on the speaking program. The campaign would confirm only that he was flying to town in time to do so.

Virtually every party leader spoke somberly of the storm's potential damage during the day, including the candidate. "Our thoughts are with the people that are in the storm's path and hope that they're spared any major destruction," said Romney, the man seeking to defeat Democratic President Barack Obama.

Although Republicans are intent on turning the campaign's focus back to the nation's sluggish economic growth and high unemployment, a comment Romney made on abortion reintroduced a topic that had taken over campaign discussion last week. In a CBS interview, he said he opposes abortions except "in the case of rape and incest and the health and life of the mother."

That underscored his difference of opinion on the subject with his running mate, Rep. Paul Ryan of Wisconsin, as well as with his own convention platform, which opposes all abortions.

Any exceptions made solely on the basis of a woman's health have drawn particularly fierce criticism from abortion foes for years, and Romney's aides said he wasn't advocating an exemption on that basis alone.

"Governor Romney's position is clear: He opposes abortion except for cases of rape, incest and where the life of the mother is threatened," said Andrea Saul, a spokeswoman.

The convention's first session lasted scarcely a minute, just long enough for the party's chairman, Reince Priebus, to rap a gavel and declare the gathering open for business. As he did, high above the floor, numbers began flashing across an electronic tally board labeled "Debt from Convention Start," meant to show the government steadily borrowing under Obama's leadership throughout the convention.

The week was turning out to be about both meteorology and politics. Romney's top aides and convention planners were juggling their desire for a robust rouse-the-Republicans convention with concern about appearing uncaring as New Orleans faced a threat from Isaac precisely seven years after the city was devastated by Hurricane Katrina.

Forecasters predicted Isaac would intensify into a Category 1 hurricane by Tuesday with top sustained winds between 74 and 95 mph, and said its projected path went through New Orleans.

Opinion polls made the presidential race nearly even as Republicans launched their convention, though it appeared Obama had a slim advantage in battleground states where the election is most likely to be decided. It was anything but certain what the impact would be on the campaign of back-to-back convention weeks, first Romney's and then the president's in Charlotte, N.C.

The economy is the number one issue by far in the polls, and Romney's surrogates sought to make sure the campaign focus stays fixed on it.

A blunt view came from Gary Hawkins, a delegate from Brandon, Miss. "We have to nominate a candidate for president. Our mission is to save America from becoming a socialistic state," he said.

In the convention hall, Priebus looked out at thousands of empty seats and a smattering of delegates in his brief turn on stage. Officials decided earlier in the week to scrap nearly all of the opening day's program when it appeared that Isaac might make a direct hit on the convention city.

That put Romney's formal nomination off by a day until Tuesday. Weather permitting, he delivers his acceptance speech on Thursday night, then embarks on a fall campaign that he hopes will propel him to the White House.

Romney's wife, Ann, is on the speaking program for Tuesday evening, and it wasn't known if he intended to be in the hall for her address.

"This week is about convincing the 10 percent of undecided voters that Romney has always been called to come out and fix broken organizations," said Sen. Roger Wicker, R-Miss., interviewed on the convention floor.

"We've got to make the case that he is uniquely qualified in this hour" he said, adding that the "country is in bankruptcy."

Sen. Rob Portman, R-Ohio, carried a similar message to his state's delegates at a morning meeting.

"It's time to stop blaming others and take responsibility," he said in a reference to the president. "There are families all over Ohio that are suffering as a result. He hasn't measured up to his own standards. "

What passed for vocal dissent within the party came from supporters of Rep. Ron Paul, a Texas Republican who ran for the presidential nomination but failed to win a primary or caucus.

Delegates loyal to him threatened a floor fight later in the week over party rules. And they staged a brief but noisy demonstration at the rear of the convention hall after Priebus completed his brief turn at the podium, holding up placards bearing their man's name. They stood in front of a permanent sign that said "We Can Do Better," appropriating Romney's pledge to fix the economy to express a preference for their man.

More than dissent, there was concern from within the party, though couched in supportive terms, that despite the political opportunity that the weak economy presents, Romney needs to broaden GOP appeal.

"This is Romney's threshold moment. He must demonstrate that he would follow the example of other Republican presidents in addressing issues important to women," Sen. Olympia Snowe, R-Maine, wrote in The Washington Post, one of several party leaders to express the view.

Not that Obama and his surrogates were letting up on that subject.

In a tweet Monday night, Obama circulated a quotation from Women's Health Magazine suggesting that Republicans would take away women's right to contraception. "Crazy as it sounds, the fight to limit or even ban birth control is a key issue in the upcoming presidential election," it said.

That was in addition to a controversy that combined rape and abortion that was triggered when the Republican candidate for a Missouri Senate seat said a woman's body has a way of preventing pregnancy in cases of "legitimate rape." Rep. Todd Akin, who opposes abortions without exception, quickly apologized for his claim, which is unsupported by medical evidence, but refused to get out of the race as Romney and other leading Republicans requested.

Polls testified to the political stakes.

An AP-GfK poll of registered voters conducted from Aug. 16 to 20 showed Obama leading Romney by 50-44 among women. That represented a narrow closing of the gap by the Republican from a survey in May, when the president led 54-39 among female voters.

Romney trailed badly among another key group. A Gallup poll taken between July 30 and Aug. 1 showed Obama winning 60 percent support among Hispanic voters, and the Republican at 27 percent, little different from 64-29 earlier in the year.

Among seniors, the group most affected by a Medicare debate that looms as central to the campaign, Romney led Obama by a margin of 52-42 in the recent AP-GfK poll. That was compared with 53-40 in May.

In Tampa, despite weather worries, Tom Del Beccaro, a California delegate and chair of the state GOP, predicted the one-day delay in full convention events would supercharge the rest of the week's meeting.

"I think there's going to be a lot of bottled up energy, and I think that's going to show," he said.

But Sally Bradshaw, a Florida Republican and longtime senior aide to former Florida Gov. Jeb Bush, was more cautious. "It's a mess all around and it's fraught with risk," she said. "It's not good for anybody — particularly the people impacted by the storm."

Vice presidential candidate Paul Ryan, speaking in his hometown of Janesville, Wis., before heading for the convention on Tuesday, said the stakes were as high as could be.

"We're not just picking the next president for a few years," he said. "We are picking the pathway for America for a generation."